The present invention relates to rotors for use in vehicle braking systems. More specifically, the present invention relates to vented disc brake rotors.
Wheeled vehicles, such as automobiles, frequently include disc brake systems for slowing the motion of the vehicle. These brake systems include a rotor that rotates with the wheel to be braked. Brake pads mounted on non-rotating calipers engage the rotor to affect braking of the vehicle. The engagement between the brake pads and the rotor is a frictional relationship that converts the kinetic energy of the moving vehicle to thermal energy.
As a result of this energy conversion, the friction generates a substantial amount of heat each time the brake pads are applied to the rotor. The temperature of the rotor can rise significantly following frequent frictional contact between the brake pads and the rotor. If the temperature of the rotor rises too high, the rotor may become damaged. As a result, the types of materials that can be utilized in disc brake rotors can be limited by the maximum temperatures they are able to withstand. For example, the use of aluminum metal matrix composite (Al-MMC) in disc brakes has been limited because of its inability to withstand excessive temperatures.
To provide a cooling effect to brake rotors, vents can be placed within the rotor. The prior art includes several examples of these vented disc brake rotors. These rotors dissipate heat generated by the friction between the brake pads and the rotor by funneling air through the vents and allowing the air to absorb a portion of the generated heat. This absorption takes away from the total heat absorbed by the brake rotor, thereby reducing the temperature of the rotor. In these designs, the cooling ability of the vents depends largely upon the quantity of air flowing through them. Consequently, the prior art contains numerous examples of vent designs.
Unfortunately, the manufacturing of vented disc brake rotors is quite complicated. Frequently, the manufacturing involves the placement of venting walls between opposing braking members to define a plurality of veins. The rotors taught by the prior art make it difficult to utilize simple manufacturing processes, such as metal die-casting. Also, the placement of venting walls within prior art rotors increases the weight of the rotors.
Due to these and other defects of the prior art, there is a need for a vented disc brake rotor that enables the use of simple manufacturing techniques, such as die-casting, while providing effective air movement through the vents of the rotor.
The present invention provides a vented disc brake rotor that has vents, or flow channels, that move air through the rotor, thereby absorbing some of the heat generated by frictional contact between the rotor and brake pads in a disc braking system. The structural features of the channels facilitate manufacturing because the rotor can be cast in a single casting step.
In one preferred embodiment, a vented disc brake rotor according to the present invention comprises first and second braking surfaces that jointly define inner and outer circumferential surfaces and a central region. A hub surface is disposed in the central region and contains a main aperture adapted for mounting the rotor onto a vehicle. A plurality of curved directing walls are disposed between the first and second braking surfaces to define a plurality of flow channels. Each flow channel extends from the inner circumferential surface to the outer circumferential surface. A curved separating wall is disposed in each flow channel and extends from a point between the inner and outer circumferential surfaces to the outer circumferential surface. The separating wall divides the flow channel into two subchannels. Also, the separating wall has a width that increases from its first end to its second end located at the outer circumferential surface. As a result, each flow channel has a total cross-sectional area that remains substantially constant from the inner circumferential surface to the outer circumferential surface. Lastly, a plurality of directing fins is disposed on the inner circumferential surface. Each directing fin defines a directing surface and is adapted to direct air into a flow channel positioned adjacent the directing fin.
Each flow channel may be opened to one of the braking surfaces, giving a gapped or intermittent configuration to the braking surface(s). This configuration facilitates manufacturing by allowing the first and second braking surfaces to be integrally formed by a singular brake member by a suitable process, such as die-casting or squeeze-casting.
While the invention is defined in the claims appended hereto, additional understanding of the invention can be gained by referencing the following detailed description of preferred embodiments and the attached drawings.